A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-energy exhaust gas flow. The high-energy exhaust gas flow expands through the turbine section to drive the compressor and the fan section.
Pneumatic systems of the aircraft utilize engine bleed air for pneumatic power. The engine bleed air is obtained from locations within the compressor section to provide air at pressures required by the pneumatic system. Pressures within the compressor section vary during engine operating cycle. At lower engine power settings pressures within the compressor section may closely match demand, however at higher engine power settings, pressures at the same compressor location may greatly exceed demand. For this reason, engine bleed air is obtained from different locations within the compressor section depending on the current engine operating conditions in an effort to maintain engine efficiency. Even using bleed air from different locations, the variation of pressures can create difficulties in matching the demand of the pneumatic system. The difference between demand of the pneumatic system and engine bleed air pressures can reduce engine operating efficiency.